“That was a brain laboratory, not a peripheral nerve lab,” he says. “I’d done all my biophysical work on the sciatic nerve of a frog. And now I was working with the brains of cats. It was neurosurgery, physiology, and pharmacology all in one. It was terribly exciting – one of the neatest times of my life. We were doing things that no one had ever been able to do before. We were discovering stuff that had just been lying there waiting to be discovered.” Hooked, Bloom never returned to St. Louis to complete his residency.

Using multi-barreled microelectrodes, the NIMH investigators would supply very small amounts of chemicals to various parts of the animal’s brain and record the activity of nerve cells, trying to examine the action of the neurotransmitters.

Bloom demonstrates stereotaxic injection techniques for studying brain function to postdoctoral fellows (left to right) Leonard Koda, James Nathanson and David Taylor at St. Elizabeth's Hospital in 1974.

Courtesy of Floyd Bloom

One of Salmoiraghi’s colleagues, Dr. Erminio Costa, helped mentor the young physician-scientist.

“In those days there were only one or two known neurotransmitters, and the NIMH labs assisted in the discovery of 20 or more additional ones. There was an explosion in known neurotransmitters,” says Costa, scientific director of the Psychiatric Institute at the University of Illinois at Chicago. “At the time nobody believed a chemical substance would be important for brain function. Everything in the brain would be electrical and neurotransmitters would be like part of a machine.

“During that period we began to discover that electrical impulses were stimulated by chemical substances.”

Bloom realized that in order to study a cat or rabbit’s brain, scientists had to anesthetize the animal. He stepped back and asked a question: “Is the response I’m seeing in the anesthetized animal predictive of what the response would have been if the anesthesia wasn’t there?” To answer that question, he and his colleagues developed methods for surgically isolating the brain.

“We found that some neurotransmitters totally changed the quality of what they did in the absence of anesthesia from what we would have predicted. Whereas others were absolutely consistent,” he says. “I think this was the first time that kind of insight had been obtained – that the actual act of studying the brain was confused by the use of the anesthetic.”